co_nutate: Calculate changes in right ascension and declination due to...

In astrolibR: Astronomy Users Library

Description

Calculate changes in right ascension and declination due to nutation of the Earth's rotation

Usage

co_nutate(jd, ra, dec)

Arguments

jd	Julian Date [scalar or vector]
ra	right ascension, in degrees (scalar or N-vector)
dec	declination, in degrees (scalar or N-vector)

Details

Calculates necessary changes to right ascension and declination due to the nutation of the Earth's rotation axis, as described in Meeus (1991), Chap 23. Uses formulae from the Astronomical Almanac (1984) and does the calculations in equatorial rectangular coordinates to avoid singularities at the celestial poles.

Value

d_ra	corrections to ra due to aberration, in arcseconds (must then be added to ra to get corrected values).
d_dec	corrections to dec due to aberration, in arcseconds (must then be added to dec to get corrected values).
eps	true obliquity of the ecliptic, in radians
d_psi	nutation of the longitude of the ecliptic
d_eps	nutation in the obliquity of the ecliptic

Author(s)

Written Chris O'Dell (2002)

R adaptation by Arnab Chakraborty (June 2013)

References

Meeus, J., Astronomical Algorithms, Willmann-Bell, 1991

See Also

nutate

Examples

co_nutate(2456469.5,253.215,-32.449)

Example output

$d_ra
[1] 16.20117

$d_dec
[1] 5.262275

$eps
[1] 0.4090281

$d_psi
[1] 12.85696

$d_eps
[1] -7.038528

astrolibR documentation built on May 2, 2019, 3:26 a.m.